This helps to reduce dirty throttling polls and hence CPU overheads. bdi->dirty_exceeded typically only helps when suddenly starting 100+ dd's on a disk, in which case the dd's may need to poll balance_dirty_pages() earlier than tsk->nr_dirtied_pause. CC: Jan Kara <jack@xxxxxxx> CC: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx> --- mm/page-writeback.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- linux-next.orig/mm/page-writeback.c 2011-12-04 12:03:06.000000000 +0800 +++ linux-next/mm/page-writeback.c 2011-12-04 12:03:07.000000000 +0800 @@ -1097,7 +1097,7 @@ static void balance_dirty_pages(struct a bdi_stat(bdi, BDI_WRITEBACK); } - dirty_exceeded = (bdi_dirty > bdi_thresh) || + dirty_exceeded = (bdi_dirty > bdi_thresh) && (nr_dirty > dirty_thresh); if (dirty_exceeded && !bdi->dirty_exceeded) bdi->dirty_exceeded = 1; -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
